Pyrolysis of Hexadecane

1997 ◽  
Vol 62 (7) ◽  
pp. 1057-1069 ◽  
Author(s):  
Elena Barteková ◽  
Martin Bajus
Keyword(s):  
Hydrogen Transfer ◽  
Coke Formation ◽  
Tubular Reactor ◽  
Frequency Factor ◽  
Mass Ratio ◽  
Pyrolysis Products ◽  
Alkyl Radicals ◽  
Secondary Reactions ◽  
Increasing Temperature ◽  
Kinetics Of

The kinetics of thermal decomposition of hexadecane was studied in a flow tubular reactor from stainless steel. The experiments were performed in the temperature range of 700 to 780 °C for the mass ratio of steam to hydrocarbon 3 : 1. The hexadecane pyrolysis took place according to the first-order reaction with a frequency factor of 3.5 . 109 s-1 and an activation energy of 162 kJ mol-1. In the pyrolysis products there were above all 1-alkenes. From alkanes, methane and ethane and less propane were formed in a higher degree. The prevailing compounds are ethene and propene whose amount increases with increasing temperature and residence time. The content of 1-alkenes higher than 1-pentene decreases with increasing conversion which gives evidence of their decomposition owing to their lower stability in comparison with the lighter 1-alkenes. The formation of dienes (1,3-butadiene and propadiene) and benzene also confirmed the course of secondary reactions. The observed higher formation of hydrogen results from the reaction of steam with coke deposited on the walls of the reactor or with hydrocarbon radicals. The evidence of the coke formation is given also by the presence of carbon oxides whose amount grew with the pyrolysis severity. The high content of 1-hexene in comparison with the other higher 1-alkenes is probably caused by the isomerization of alkyl radicals by 1,5-hydrogen transfer.

Pyrolysis of methylcyclohexane

1987 ◽  
Vol 52 (6) ◽  
pp. 1527-1544 ◽  
Author(s):  
Ulrika Králíková ◽  
Martin Bajus ◽  
Jozef Baxa
Keyword(s):  
Activation Energy ◽  
Coke Formation ◽  
Tubular Reactor ◽  
Frequency Factor ◽  
Order Reaction ◽  
The Other ◽  
First Order ◽  
Consecutive Reactions ◽  
Secondary Reactions ◽  
Kinetics Of

The kinetics of pyrolysis of methylcyclohexane was investigated from the viewpoint of coke formation in a steel tubular reactor (S/V = 6·65 cm-1) at 0·1 MPa, 700 to 820 °C and residence time 0·01 to 0·24 s. Decomposition of methylcyclohexane proceeds as a first order reaction with a frequency factor 6·31 . 1015 s-1 and activation energy 251·2 kJ mol-1. The course of secondary reactions associated with the formation of coke is discussed. Investigation of coke formation showed a greater tendency of methylcyclohexane to coking in comparison with heptane. A prominent role plays the course of dehydrogenation of cycloalkane radicals up to aromates, this being reflected by the overall conversion of methylcyclohexane, and, on the other hand the thus formed aromates enter the consecutive reactions leading to coke.

scholarly journals Oxidation Kinetics of Propane-Air Mixture over NiCo2O4 Catalyst Emitted from LPG Vehicles

2017 ◽  
Vol 12 (2) ◽  
pp. 191
Author(s):  
Suverna Trivedi ◽  
Ram Prasad ◽  
S. Chadha
Keyword(s):  
Oxidation Kinetics ◽  
Plug Flow ◽  
Tubular Reactor ◽  
Frequency Factor ◽  
Reaction Engineering ◽  
Precipitation Method ◽  
Air Oxidation ◽  
Temperature Ranges ◽  
Co Precipitation ◽  
Kinetics Of

This paper describes the kinetics of catalytic air oxidation of propane. The kinetics data were collected in a plug flow tubular reactor. The experiments were performed over the NiCo2O4 catalyst prepared by co-precipitation method followed by calcination at 400 oC. The kinetic data were collected under the following conditions: 200 mg of catalyst, 2.5 % of propane in air, total flow rate of 60 mL/min, and temperature ranges of 130-170 oC. The data were fitted to the power law rate equation. The activation    energy and frequency factor were found to be 59.3 kJ/g mol and 2.9×108 (mol)0.47.L0.53/g cat.h, respectively. Copyright © 2017 BCREC Group. All rights reservedReceived: 20th November 2016; Revised: 26th February 2017; Accepted: 26th February 2017How to Cite: Trivedi, S., Prasad, R., Chadha, S. (2017). Oxidation Kinetics of Propane-Air Mixture over NiCo2O4 Catalyst Emitted from LPG Vehicles. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (2): 191-196 (doi:10.9767/bcrec.12.2.798.191-196)Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.2.798.191-196 

Molar Kinetics in Catalytic Hydrocracking of Asphaltenes

2012 ◽  
Vol 455-456 ◽  
pp. 533-539
Author(s):  
Sheng Jian Zhang ◽  
Ying Xian Zhao
Keyword(s):  
Coke Formation ◽  
Reaction Times ◽  
Initial Value ◽  
First Order ◽  
First Order Kinetics ◽  
Formation Probability ◽  
Liquid Products ◽  
Secondary Reactions ◽  
Gas Products ◽  
Kinetics Of

The hydrocracking of a pentane-insoluble asphaltene over NiMo/γ-Al2O3 was investigated in a microbatch reactor at 703 K. The cracking kinetics of the asphaltene was analyzed on a total molar basis. The first-order kinetics fits the experimental data in reaction times ≤30 min adequately, to give the rate constant of 0.0498 min-1. For reaction times over 30 min, however, secondary reactions such as coke formation could become significant. The formation probability of gas products decreases from the initial value of circa 0.8 to a stable level of 0.6 in 30 min, and the formation probability of liquid products increases from 0.2 to 0.4 accordingly.

Kinetics of Thermal Injury in Cells

1977 ◽  
Vol 99 (3) ◽  
pp. 155-159 ◽  
Author(s):  
N. A. Moussa ◽  
J. J. McGrath ◽  
E. G. Cravalho ◽  
P. J. Asimacopoulos
Keyword(s):  
Constant Temperature ◽  
Thermal Injury ◽  
Frequency Factor ◽  
Working Relationships ◽  
Kcal Mole ◽  
Cell Temperature ◽  
Initial Cell ◽  
Increasing Temperature ◽  
Kinetics Of ◽  
Microscope Stage

HeLa cells, suspended in solution, were subjected to well-defined temperature protocols on a microscope stage specifically designed for this purpose. Simultaneously, the appearance of the first irreversible morphological change in the cells was monitored and used as an indicator of damage. For constant temperature protocols, an Arrhenius relationship was found between the measured damage time and the cell temperature, yielding an activation energy of 249 kJ/mole (59.5 kcal/mole) and a frequency factor of 9.09 × 1036 s−1. On the basis of this result and of Henriques’ damage integral concept [1], working relationships have been derived to express the damage time for two additional temperature protocols; viz., 1 a linearly increasing temperature, and 2 a linearly increasing temperature followed by a constant temperature. These relationships show the dependence of the damage time on the heating rate, the maximum attained temperature, the damage kinetics and the initial cell temperature.

Pyrolysis of unsubstituted bicyclic hydrocarbons and gas oil

1982 ◽  
Vol 47 (7) ◽  
pp. 1838-1847 ◽  
Author(s):  
Martin Bajus ◽  
Jozef Baxa
Keyword(s):  
Stainless Steel ◽  
Elemental Sulphur ◽  
Raw Material ◽  
Gas Oil ◽  
Mass Ratio ◽  
Reaction Products ◽  
Pyrolysis Products ◽  
Reactor Material ◽  
Tubular Reactors ◽  
Stainless Steel Reactor

Pyrolysis of tetraline, decaline, 1,1'-bicyclohexane, cyclohexylbenzene and gas oil was studied in stainless steel and quartz flow tubular reactors at 780 and 800 °C, residence time 0.08 to 0.5 s and at the mass ratio of steam to the raw material changing from 0.5 to 1.5. The effect of reaction temperature, the mass ratio of steam to the raw material, reactor material and of the added elemental sulphur on the yields of individual reaction products is reported. Of bicyclic hydrocarbons, condensed hydrocarbons are more stable than those with noncondensed rings, cyclanoaromates being more stable than bicyclanes. Pyrolysis of gas oil in the stainless steel reactor yields greater amounts of ethylene, propylene, butadiene and smaller amounts of methane and ethane, compared to the pyrolysis carried out under identical conditions in the quartz reactor. Elemental sulphur increases the conversion of gas oil into gaseous pyrolysis products.

scholarly journals Kinetic Studies of Cs+ and Sr2+ Ion Exchange Using Clinoptilolite in Static Columns and an Agitated Tubular Reactor (ATR)

2021 ◽  
Vol 5 (1) ◽  
pp. 9
Author(s):  
Muhammad Yusuf Prajitno ◽  
Mohamad Taufiqurrakhman ◽  
David Harbottle ◽  
Timothy N. Hunter
Keyword(s):  
Adsorption Capacity ◽  
Tubular Reactor ◽  
Process Intensification ◽  
Kinetic Studies ◽  
Breakthrough Curves ◽  
Maximum Adsorption Capacity ◽  
Batch Studies ◽  
Shear Mixing ◽  
Natural Clinoptilolite ◽  
Kinetics Of

Natural clinoptilolite was studied to assess its performance in removing caesium and strontium ions, using both static columns and an agitated tube reactor (ATR) for process intensification. Kinetic breakthrough curves were fitted using the Thomas and Modified Dose Response (MDR) models. In the static columns, the clinoptilolite adsorption capacity (qe) for 200 ppm ion concentrations was found to be ~171 and 16 mg/g for caesium and strontium, respectively, highlighting the poor material ability to exchange strontium. Reducing the concentration of strontium to 100 ppm, however, led to a higher strontium qe of ~48 mg/g (close to the maximum adsorption capacity). Conversely, halving the column residence time to 15 min decreased the qe for 100 ppm strontium solutions to 13–14 mg/g. All the kinetic breakthrough data correlated well with the maximum adsorption capacities found in previous batch studies, where, in particular, the influence of concentration on the slow uptake kinetics of strontium was evidenced. For the ATR studies, two column lengths were investigated (of 25 and 34 cm) with the clinoptilolite embedded directly into the agitator bar. The 34 cm-length system significantly outperformed the static vertical columns, where the adsorption capacity and breakthrough time were enhanced by ~30%, which was assumed to be due to the heightened kinetics from shear mixing. Critically, the increase in performance was achieved with a relative process flow rate over twice that of the static columns.

scholarly journals Kinetics of drying of basil leaves (Ocimum basilicum L.) in the infrared

2012 ◽  
Vol 16 (12) ◽  
pp. 1346-1352 ◽  
Author(s):  
Renata C. dos Reis ◽  
Ivano A. Devilla ◽  
Diego P. R. Ascheri ◽  
Ana C. O. Servulo ◽  
Athina B. M. Souza
Keyword(s):  
Experimental Data ◽  
Ocimum Basilicum ◽  
Coefficient Of Determination ◽  
Chisquare Test ◽  
The Mean ◽  
Drying Curves ◽  
The One ◽  
Increasing Temperature ◽  
Air Circulation ◽  
Kinetics Of

The objective of this paper was to model the drying curves of the leaves of basil (Ocimum basilicum L.) in the infrared at temperatures of 50, 60, 70 and 80 ºC and to evaluate the influence of drying temperature on the color of dried leaves. Drying was conducted in infrared dryer with temperature and greenhouse air circulation. Experimental data were fitted to eight mathematical models. The magnitude of the coefficient of determination (R²), the mean relative error (P), the estimated mean error (SE) and chisquare test (χ2) were used to verify the degree of fitness of the models. From the study it was concluded that: a) the behavior of the drying curves of basil leaves was similar to most agricultural products, the drying times in the infrared were less than the drying times in an oven with air circulation, b) the mathematical drying model proposed by Midilli et al. (2002) was the one which best adjusted to the experimental data, c) the diffusion coefficient ranged from 9.10 x 10-12 to 2.92 x 10-11 m² s-1 and d) the color of the samples was highly influenced by drying, becoming darker due to loss of chlorophyll with increasing temperature.

Charakterisierung und Kinetik des in der Rattenplacenta vorkommenden mikrosomalen Enzyms, das den Wasserstoff-Transfer von Oestradiol auf Androstendion katalysiert / Characterization and Kinetics of the Microsomal Enzyme of Rat Placenta which Functions as a “Transhydrogenase” between Estradiol-17β and Androstenedione

1971 ◽  
Vol 26 (7) ◽  
pp. 710-719 ◽  
Author(s):  
Kunhard Pollow ◽  
Barbara Pollow
Keyword(s):  
Hydrogen Transfer ◽  
Microsomal Fraction ◽  
Close Relation ◽  
Inhibitory Effect ◽  
Magnesium Ions ◽  
Michaelis Constant ◽  
Temperature Optimum ◽  
Optimum Ph ◽  
Kinetics Of ◽  
Estradiol 17Β

The microsomal fraction of rat placenta contains a 17β-hydroxysteroid-oxidoreductase which transfers hydrogen from position 17 of estradiol to androstenedione. This hydrogen transfer is dependent on NAD, NADP as cofactor is without effect. The optimum pH is at 6,9. In the presence of NAD the Michaelis constant for estradiol is 4,17 · 10-5м at pH 7,4. In the presence of androstenedione in the incubation medium the Km-value for estradiol is decreased, which indicates an increased affinity for the enzyme. The temperature optimum of the enzyme is 38 °C. Addition of SH-blocking agents inhibited the enzyme activity. Zinc and magnesium ions had an inhibitory effect on the “transhydrogenase” and B-NADPT specifically labelled from [1-T]-glucose showed that the non-effect of NADP on transhydrogenation from estradiol to androstenedione resulting in reduction of position 17 is not due to different stereospecifity.The results show a close relation between the oxidative metabolism of estradiol and the reduction of androstenedione, indicating that estradiol-17β, as the preferred hydrogen-donating substrate, is an essential component of the androstenedione-hydrogenating system in the microsomal fraction of rat placenta.

Kinetics of hydrogen-transfer isomerizations of butoxyl radicals

2010 ◽  
Vol 12 (28) ◽  
pp. 7782 ◽  
Author(s):  
Jingjing Zheng ◽  
Donald G. Truhlar
Keyword(s):  
Hydrogen Transfer ◽  
Kinetics Of
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